This board is a version of our generic Battery-board which includes a DHT11 dual humidity/temperature sensor from AOSONG. This sensor can read positive temperatures (from 0°C to 50°C) with 1.0°C precision and ±2°C accuracy. It also reads humidities in the 20-80% range with 1.0% precision and 5% accuracy. This sensor is typically suited for indoor HVAC applications.
Figure 1 : panStamp Battery-board-DHT11 for wireless applications
In order to use Battery-board-DHT11, you will first have to download this Arduino library for DHT11 and place it with the rest of Arduino libraries. Then you only need to program a panStamp with our sample temphumpress application compiled with the TEMPHUM definition enabled from sensor.h. You will also need to enable DHT11 as the sensor to be used by the application:
By default, temphumpress takes Vcc as the actual battery voltage. However, all battery-boards have Analog 7 pin (panStamp 12th pin) directly connected to the battery. When using this application on a Battery-board, we advise enabling battery monitoring via the Analog 7 pin. From temphumpress.ino we have to uncomment the VOLT_SUPPLY_A7 definition:
Figure 2 : Base-board-DHT11 with panStamp and AA battery
Connection between panStamp and DHT11 sensor is quite simple so in case you want to create your own DHT11-base board you will only need to follow this diagram, which makes use of the same pins than our Battery-board-DHT11:
As you can see, the DHT11 is directly powered from the Arduino digital pin 15 (Analog 1). This lets the panStamp unpower the sensor whilst in sleep mode, reducing the current consumption to the maximum. For any other hardware reference please refer to our generic Battery-board product.
Firmware-side, when programmed with our sample temphumpress application, the board periodically sends temperature/humidity readings according to the value programmed in the TX_INTERVAL register, saved in EEPROM. This interval is 255 (0xFF) by default in "fresh"panStamps so you will need to program your desired interval after programming the module for the first time. After transmitting the reading, the panStamp enters the sleep mode, disconnecting most peripherals until the next transmission and hence drastically reducing the current consumption.